The present invention relates generally to radio frequency identification (RFID) and more specifically to interpreting data generated by RFID systems.
A conventional RFID system involves locating RFID tags within read zones of RFID readers. Each of the RFID tags typically includes an identification sequence enabling identification of the tag, when it responds within the read zone of an RFID reader. The precision with which the RFID system can locate an RFID tag is determined by the size of the read zones of each of the RFID readers. A typical RFID system builds a data set from RFID tag reads, where each read indicates a unique identifier, has an associated time stamp, and indicates a read zone. When the read zones of RFID readers overlap, analysis of information such as the read rate of a specific RFID tag by different readers can be used to determine the zone in which the RFID tag actually resides.
Many RFID systems are deployed in support of real world business processes. The term business process is used here to describe a sequence of activities that are performed in response to predetermined conditions in a real world environment. Examples of business processes include, but are not limited to, assembly, packaging, sorting, shipping and receiving. As assets move through a supply chain, they are typically the subject of numerous business processes. Significant amounts of data can be generated by RFID systems related to movement of assets during the performance of business processes. The data can be collected and rules and/or queries (collectively filters) can be applied to the collected data. When location precision is limited to zones defined by the placement of RFID readers, placement of the RFID readers becomes important to obtaining information that is relevant to coarse asset movements. For example, determining whether goods are within a specific staging area typically involves placing RFID readers in such a way that the read zones of a set of readers only cover the staging area. Such a system tends to be static. Therefore, changing a business process can necessitate moving the RFID infrastructure (i.e. the RFID readers and any associated cabling and sensor hardware) in order to obtain information that is useful to support the new business process. In addition, the information concerning motion of assets is limited to dwell times within and transitions between read zones.